Workstations, such as workbenches, base cabinets with countertops, and equipment such as large power tools, are used to support materials and projects while operations are performed on them. To do this job well, workstations are typically built with strength and rigidity, and either weighted or attached to a wall or floor so that they may adequately withstand the loads applied to them or the toppling forces generated within them. For example, a board may be clamped to a workbench and cut with a saw. During this operation it is desirable for the workbench to hold the board with little or no motion.
It is often necessary to move a workstation. Reasons include sharing the use of the floor space occupied by the workstation for other purposes, the need to re-arrange a work area or flexible manufacturing cell, and the need to move projects and tools around a work area or production floor while the projects and tools are on the workstation itself.
These two needs of stability and portability are at odds with one another. The user of a workbench, for example, is faced with a decision: either choose a bench which is heavy or attached and therefore serves well as a work platform, or choose a bench that is lightweight and freestanding to provide moveability.
To make it possible to move a heavy workstation, wheels having casters may be added to the base. To prevent undesired motion, the casters are sometimes equipped with a locking mechanism to inhibit or prevent both swivel and wheel rotation. Alternately, casters may be mounted on a mechanism that allows them to be raised and lowered as needed.
Current, commercially available air bearings are used to move heavy equipment, but are generally complicated and therefore impractically expensive to dedicate to one item.
In U.S. Pat. No. 4,240,773 issued to Terry, an apparatus is described for the purpose of transporting heavy loads on commercially available air bearings. The apparatus is built for the single specific task of moving paper rolls, and the load must be relatively well centered.
U.S. Pat. No. 3,513,934 issued to Crowley shows a general-purpose base for lifting and transporting. This device uses a membrane with apertures that are cut and registered to the base. The floor seal is accomplished by means of a free-edged skirt with perforations.
In U.S. Pat. No. 3,313,367, issued to Swedburg, a single bearing is shown with a resonating chamber.
Raise/lower arrangements are not common since they are typically expensive and/or awkward. In addition, there are other disadvantages to wheels:
1) Wheeled bases do not permit a work surface to be solid and stable. Even casters that lock both swivel and wheel rotation never allow a workbench, cabinet, or machine tool to sit absolutely solidly. A work surface that jiggles even slightly is frustrating, unprofessional, and potentially unsafe to work on.
2) Wheels do not roll easily across the typical workshop or production floor. Caster wheels bearing heavy loads are difficult to push across a shop floor. Rolling resistance for a fully loaded cabinet is often so high that multiple physically strong people are needed to move loaded cabinets. Minor floor irregularities can become obstacles.
3) Wheels and casters, in particular, make it difficult to precisely position or steer heavy objects. Casters must swing before tracking predictably, and small motions or alignments are difficult. When a wheeled bench or cabinet is moved against a wall, adjacent benchtop, or other object, it often rolls back slightly, from hysteresis, and leaves an undesirable gap.
4) Wheels and associated hardware create a space under which debris may collect.
5) Wheels significantly raise the height of the object.
6) Wheels and associated hardware can create a trip hazard. If the wheels are moved further inboard under the object to eliminate or reduce protrusion, the footprint is reduced and stability is sacrificed, creating a tipping or rollover hazard.
7) Rolling wheels can create pinch hazards for toes.
8) Wheels concentrate supported loads over a small area. The resulting high contact pressure can damage the floor surface or objects over which the wheels roll.
It is therefore an object of the invention to provide an easy means of moving heavy loads, yet to allow the loads to be steady and stable when parked.
It is another object of the invention to provide a versatile base that may be placed under any object to be moved across a relatively smooth surface.
It is another object of the invention to provide a heavy, solid workbench that may be easily moved, yet is steady and stable when parked.
It is another object of the invention to provide a multiple air bearing assembly that is self-balancing and can tolerate substantially off-balance loads without adjustment.
It is another object of the invention to provide an air bearing that, when unpressurized, retracts fully so that it is not damaged by dragging across the floor under load.
It is another object of the invention to provide a multiple-bearing base that supports the load redundantly, so that if air pressure is lost in one bearing (for example, when traversing a gap in the floor), another bearing or bearings will automatically compensate for the lost lift and continue to carry the load.
It is another object of the invention to provide an easily manufactured, simple, low-cost, readily-customized multiple-bearing assembly.
It is another object of the invention to provide means by which objects may be precisely maneuvered and positioned with free omnidirectional motion.
It is another object of the invention to protect floors from damage by distributing the load over a large area both while flying and when parked.
It is another object of the invention to provide means to lock a moved object into the precise desired position without further motion.
It is another object of the invention to provide means for creating the widest possible footprint under an object for maximum stability and resistance to tipping loads.
It is another object of the invention to provide a continuous closed base which does not allow the accumulation of debris, and therefore reduces cleaning efforts.
It is another object of the invention to provide a base with no protruding objects which create potential trip hazards or obstacles to cleaning equipment such as brooms.
It is another object of the invention to provide a method by which a person of nearly any strength and without special training, equipment, or assistance, can easily and safely move loads.
It is another object of the invention to provide a method of moving objects without danger of injuring toes or objects by rolling over them.